This invention relates to a personal watercraft and more particularly to an improved direct fuel injection system for such watercraft.
Personal watercraft like other applications that employ primarily internal combustion engines as their prime movers are experiencing considerable pressure to improve not only their performance but also their exhaust emission control. This has caused the manufacturers of these types of watercraft to seriously consider direct cylinder injection for the engine.
By embodying direct cylinder injection is possible to obtain significant improvements in fuel economy and also exhaust emission control. One of the main reasons for this is that direct cylinder injection may be accompanied by stratification or lean burning operation that achieves these ends.
However, there is a significant problem in connection with applying these types of devices to personal watercraft. A personal watercraft by its very nature is quite small and the engine compartment and space for the engine and its auxiliaries is quite limited.
As is well known, personal watercraft are generally designed to be operated by a single rider operator who might carry no more than two or three additional passengers. Thus, not only is the space limited but the accessibility of the engine compartment also is limited.
When direct cylinder injection is employed, it is necessary to employ a high pressure pump in order to elevate the fuel to sufficient pressure as to offer consistent injection into the combustion chamber of the engine. That is, direct injection requires considerably higher injection pressures than manifold type of fuel injection.
Normally, this high pressure can be achieved only through the use of positive displacement pumps and these pumps generally are driven from the engine output shaft. However, the pump drive presents a significant problem in personal watercraft because of their small space availability.
It is, therefore, a principal object of this invention to provide an improved and simplified fuel injection pump drive arrangement for a personal watercraft.
It is a further object of this invention to provide an improved, simplified, and compact way in which a fuel injection pump can be driven off the engine output shaft and maintain a small compact engine and engine component layout.